Move scoped_test_dir.* and test_io_thread.* from edk/test to edk/system/test.

mojo/edk/embedder/embedder_unittest.cc

Index: mojo/edk/embedder/embedder_unittest.cc
diff --git a/mojo/edk/embedder/embedder_unittest.cc b/mojo/edk/embedder/embedder_unittest.cc
index cbb698248fc1d2c370a3775c6604fafca68dff4f..8f39b151acb7b678a3e8a01ac0a27d7501ef982c 100644
--- a/mojo/edk/embedder/embedder_unittest.cc
+++ b/mojo/edk/embedder/embedder_unittest.cc
@@ -17,20 +17,19 @@
 #include "mojo/edk/embedder/platform_channel_pair.h"
 #include "mojo/edk/embedder/test_embedder.h"
 #include "mojo/edk/system/mutex.h"
+#include "mojo/edk/system/test/test_io_thread.h"
 #include "mojo/edk/system/test/timeouts.h"
 #include "mojo/edk/test/multiprocess_test_helper.h"
 #include "mojo/edk/test/scoped_ipc_support.h"
-#include "mojo/edk/test/test_io_thread.h"
 #include "mojo/public/c/system/core.h"
 #include "mojo/public/cpp/system/handle.h"
 #include "mojo/public/cpp/system/macros.h"
 #include "mojo/public/cpp/system/message_pipe.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
-namespace mojo {
-
-using test::TestIOThread;
+using mojo::system::test::TestIOThread;
 
+namespace mojo {
 namespace embedder {
 namespace {